Strategy of Driving the PiP Effectively

I would advise against it, not for efficiency reason but to prolong your battery life. If you are driving in city traffic (below 45 mph), accelerating with battery is fine. However, you are merging into highway, do it in HV mode. Remember, the battery would assist the ICE while it is warming up, so plan ahead.

I have noticed that PiP maintains the battery charge slightly different.

If I switch to HV mode with 8 EV miles remaining and merge into highway, the EV mile will drop to say 7 miles. That's because the battery is used to assist ICE while warming up. This EV-Boosted warmup results in 50+ MPG but it borrowed one EV mile.

After ICE warmed up, it would return the borrowed battery charge. You would expect the gas engine to charge the battery back to 8 EV miles but it doesn't. It recharges back to about 7.5 miles because I am already at highway speed. The remaining 0.5 miles is reserved for regen brake. The car is pretty smart.

 

I have found that it is much harder to start stacking if you had let EV miles drop to 0 vs. leaving 0.1 available. With the former it takes some sort of downhill slope to pop you back into the positive EV mile range. In the case of the later, simple stop and go traffic will allow you to start stacking.

 

Right. If I don't want to wait until I slow down, I can resume regen right away by shifting to B mode.

A regular Prius is sensitive to use ICE to brake so it is not worth risking starting the ICE just to capture a little more regen energy. With PiP in EV mode, there is no risk of ICE starting in B mode.

 

Yes, but not because it regen less in HV mode. The battery state of charge required to take you back into EV mode is set high.

If I recall, EV->HV switch is at 23% SOC. HV->EV switch is at 25% or 26% SOC.

 

Agreed. When it would eventually pop back up with EV miles it was obvious that regen had been occurring because the number would jump from 0 to 0.8 or something like that. It didn't start at 0 then move to 0.01, 0.02 etc..

 

I was suggesting to prolong the battery life beyond normal use.

You can drive any way you like and the battery should last longer than the warranty period. The battery has an upgraded cooling hardware (two blowers and intakes). The battery monitoring includes cell pressure (per a SAE paper) on top of the normal voltage, temp, etc.

 

As far as I know, all batteries will degrade over time. They may not go dead but their performance level will be reduced. I think the warranty only covers dead battery and not reduced performance. I have read that extreme heat will reduce the lift span of a battery so you definitely want to keep your car interior as cool as possible.

 

It is the combination of heat and high battery state of charge. The owner's manual has a tip to avoid it. PiP charging has a timer to charge it up right before you drive out. The goal is to avoid the car fully charged sitting under the sun.

PiP charge time is 3 hours with a regular plug or 1.5 hours with L2. You can set the timer to start charging at 2pm or 3:30pm (L2), to avoid charging at peak heat noon.

 

I think it applies to NiMh hybrids too. Lithium may be more sensitive because a full charge sits at 85% SOC. NiMh hybrid's normal (6 bars) SOC is 60%, 8 full bars is 80%.

The warranty period should be calculated with the worse case scenario in mind. Toyota is conservative.

 

With warmer temperatures I have noticed that the driving route does influence the efficiency of the ICE warmup phase. On level terrain the computer indicates the ICE is getting 50 to 60 MPGs. If the ICE is triggered while going up hill or during acelleration drops the gauge drops to the 20 to 25 mpg range.

 

did you join Blink? They are waiving the membership fee, and it's only $1/hour if you're a member. (at least here in Oregon). Also, they have a 5 minute grace period at the end of the hour. I find that if I unplug at 64 minutes, my PiP is 90-95% charged, and it "only" costs me a buck to get there, vs. paying another whole dollar to get that last ~5% of charge. It's still not entirely cost effective, but it lets me stretch the time between visits to the gas station, and I enjoy driving the car more in EV mode.

 

Just to clarify something for me: With ChargePoint, the charging fee is determined by the owner of the station. It may be free or connect-time-based or kwh-based. Are the rates with Blink determined by the network, like what kind of account you have with them, rather than by the owner of the charging station?

 

Exactly! If memory serves; It's $2/hour for non-members, using a credit card, $1.50/hour if you are a basic member, or $1/hour if you are a Premium member. The premium membership carries a fee, but they have a note on their site stating that they will be waiving the fee for at least the duration of 2013.

 

Sounds to me like the Chargepoint model is a better fit for retailers who want to provide a perk to get customers in their door. As opposed to those who want to install EV stations as a revenue generator. Not expressing a judgement; either would be a reasonable business objective.

 

My driving style is probably unusual, so this may not be the case for most drivers, but that warm up cycle is a pure fuel waster. There are three spots on my commute that are better suited for ICE power. Each spot is very short - about 15-30 seconds. They are far enough apart that the ICE cools down between them and has to repeat the warm up cycle each time. The worst part is that two of them always have a red light at the end so I can't even take advantage of the ICE to push me along. I just have to sit at a stoplight with the ICE running every morning. Every morning the ICE runs for about 6 unnecessary minutes because of the warmup cycle. It's not helping reduce pollution because I'm not using the ICE again after the warm up cycle, at least not until it has cooled down again, thus defeating the purpose.

It also seems as thought the PiP keeps a ledger tracking the SOC and the origination of the charge. Not only does it track how much charge it "borrowed" while the ICE warms up and return the balance, it also tracks how much was generated by regen and feels entitled to use it even with the car in HV mode. For example, I crest a hill in HV mode with 5.0 miles of range left. The hill is steep and at the bottom I have 6.5 miles of EV range. Even though the PiP is in HV mode and I'm traveling at 70 mph, it will go into EV-assist mode until the range is back to 5.0 miles (the display will still show the car in HV mode, but you can watch the EV range ticking down while you drive). The only way I've been able to stop that behavior is to switch to EV mode and back to HV mode.

 

That's not a good scenario for PiP at all. I assume you can't change the route or time the red light differently. If the ICE is running at the red light, it is also charging the battery so it doesn't go wasted.

Subsequent warm ups should be shorter. The goal is for the catalytic converter to heat up to 380 deg F.

Depending on the length of your commute, you may want to use gas during those spots that would start the ICE. Switch to HV mode before reaching those ICE starting spots so ICE can shut down at red lights. The goal is to perform the warm up while in motion rather than at rest. See if that helps.

 

Here is a scenario and maybe someone can tell me which one would give me the best efficiency. If I'm traveling 100 miles and want to maximize my mpg, would I:
(A) Let the car do it's own thing and use up all the EV miles in the beginning and run the rest of the trip in HV?
(B) Switch to HV for accelerating, climbing hills & anything over 45mph & switch back to EV for a constant speed?
(C) Put it in pwr mode or accelerate hard enough to get the HSI in the the pwr band to use the HV to assist in the acceleration instead of using EV 100% for accelerating?

 

A vs B is debatable depending on other variables, but definitely not C.